Mutations in the BRCA1 and BRCA2 genes are known to lead to an increased risk of cancer in humans. Women with an abnormal BRCA1 or BRCA2 gene have up to a 60% risk of developing breast cancer by age 90. For ovarian cancer, woman with BRCA1 or BRACA2 mutations have an increased risk of about 55% and 25% respectively. Many women with these genes are given the option to undertake prophylactic surgery including breast or ovary removal to reduce the cancer risk. Such decisions are incredibly difficult for healthy patients to make, especially for those women who have plans to bear children. Rather than relying on population level statistics, patients would benefit from a more individualised risk analysis based on their specific situation.
A number of studies have recorded a large amount of observational data from women with the BRCA1 and BRCA2 genes together with the subsequent incidence (or otherwise) of cancer. Statistical techniques can be used to determine which individual factors play a dominant role in determining cancer risk and to develop a personalised risk profile based on, for example, age, number of children, diet, whether they smoke and other genetic information. These models can also be used to produce personalised projections indicating the likely timescales of disease onset.
The decision to take elective surgery is a highly personal one and needs to be informed by as much information as possible. By providing a personalised risk profile taking account of the effect of all the relevant factors women are able to make an informed decision as to whether or when to have preventative surgery.